The International Cessna^® 170 Association

I would like to purchase a battery charger for my 170B. I have a Concord RG-25. Does anyone have any recommendation on chargers? I am looking at the BATTERYMINDER MODEL 128CEC1-AA-S5 which says it's recommended for Concord batteries. It is fairly expensive.

http://www.batteryminders.com/batterymi ... esulfator/
http://www.aircraftspruce.com/catalog/e ... -14349.php

I'm always amused at the number of presentations seen live and on the internet by sellers of battery chargers. The spiels often go into great detail about how superior their system is to all others and how using anything but the most sophisticated chargers can ruin your battery and give you hives.

ALL batteries which are legal to install in a Cessna 170 must be capable of serving and BEING SERVED by the Cessna 170 original charging system. This includes the latest, greatest, high-tech Wet/Dry/Gel/AGM/ETC aircraft batteries. If the battery cannot be used safely and reliably with the original generator/vibrating-points charging system of these 1948-56 airplanes then the battery is not approved for that installation.

So... if the original charging system has all the technology of a 1936 John Deere tractor.... WHY does a particular battery require a solid-state, mystery-intelligence charger?
Answer: It doesn't.

An ordinary, self-regulating automobile charger will adequately serve your battery. If you are looking for a "maintenance" type charger, then a common automotive "maintenance" charger will also work just fine.

For that purpose, here is the $29 one from Sears that I've used for the last EIGHT years on the SAME Concorde battery I use: http://www.sears.com/diehard-battery-ch ... aQodprUGLQ

Here's another good one for only $19 (Wal-Mart): https://www.walmart.com/ip/Black-Decker ... 3=&veh=sem

I own both models.
BTW, I often leave the maintenance charger on the airplane for a week, then transfer it to my lawn-tractor for a week, then to my tractor for a week, then to my boat for a week, then repeat the process. The other one is on the grandkids go-cart for a week and then on the bull-dozer for a week, then the ranch-Jeep for a week, etc etc.

i can only recommend you do some research on batteries and see what you come up with is what is suggested here.

George, do you disconnect the battery from the aircraft bus when you charge or just connect it and go? The reason I ask is the Concord website documentation goes into great detail about how dangerous it is to change he the battery in the airplane. The just want to make sure I'm not overlooking something.

Looks like I can just use the same battery tender I use on my four wheelers and other vehicles.

nippaero wrote:George, do you disconnect the battery from the aircraft bus when you charge or just connect it and go? The reason I ask is the Concord website documentation goes into great detail about how dangerous it is to change he the battery in the airplane. The just want to make sure I'm not overlooking something.

Looks like I can just use the same battery tender I use on my four wheelers and other vehicles.

The battery manufacturers are very careful regarding their liabilities with regard to what they print in their manuals. Yes, the most-pristine advice is to remove the battery for charging.

However, keep in mind that most of the time spent charging your battery ...is done with it installed with the engine running.... and IN FLIGHT!

I perform my "maintenance charging" while it is installed, ready for flight. My airplane has the external power-plug (AN2552-2) installed in accordance with AK70B52-9, and is continuously connected to that ground service plug, which I use for charging in the hangar. (In fact, it's the main reason I accomplished that modification.... and yes, ... I consider it "original" since it's a C-170B Service Kit designed by Cessna.)

George, do I remember correctly that your aux plug is mounted on the firewall with the plug opening facing down? One of these days I am going to install the one you got for me. Would be nice a bit farther from the prop, but don't want to get into running cables back to the back of the fuge.

nippaero wrote:George, do you disconnect the battery from the aircraft bus when you charge or just connect it and go? The reason I ask is the Concord website documentation goes into great detail about how dangerous it is to change he the battery in the airplane. The just want to make sure I'm not overlooking something.

Looks like I can just use the same battery tender I use on my four wheelers and other vehicles.

Ever since I saw a Luscombe that had burned to the ground due to a battery and/or charger failure, I ALWAYS remove the battery from by airplane to charge it (assuming I haven't flown enough for the aircraft charging system to do its job ). (BTW, my 40-year old automotive trickle charger works just fine.)

Here is the problem with George's logic. The old battery chargers where not floating point chargers like your aircraft regulator either. They relied on time.

If you want to use an old car style battery charger and stand around and monitor the new battery with a VOM to make sure you don't over or under charge it, have at it. It will work find.

However, if you want to plug it in an walk away and not come back to a over or under charged battery, get the automatic charger that is built for the type of battery you are charging so that the automatic system that regulates/shuts off the charger detects the correct moment to shut off or go to trickle.

And here is a tip. Lead acid car batteries are NOT the same as lead acid airplane batteries and neither are the same as a Gas Recumbent Mat (RG) airplane battery.

Yes the correct battery charger is expensive. So is a destroyed aircraft battery which has been incorrectly charged. I've seen it more than once. Leroy destroyed our RG battery using old school car chargers like he would charge a car battery, the newly installed battery of the '54 170 which was up for raffle and recently won at our airport suffered the same fate when someone just through on that car charger laying in the hanger. I will not put any car charger on my RG (or airplane lead acid) battery and simply walk away thinking the auto feature will take care of it.

And if you want to know if you should remove the battery for any serious charging, specially should you over charge the battery and spew all sorts of corrosive gas in your engine compartment, come look at my corroded fire wall from just this practice.

Bruce Fenstermacher wrote:Here is the problem with George's logic. The old battery chargers where not floating point chargers like your aircraft regulator either. They relied on time.

If you want to use an old car style battery charger and stand around and monitor the new battery with a VOM to make sure you don't over or under charge it, have at it. It will work find.

However, if you want to plug it in an walk away and not come back to a over or under charged battery, get the automatic charger that is built for the type of battery you are charging so that the automatic system that regulates/shuts off the charger detects the correct moment to shut off or go to trickle.

And here is a tip. Lead acid car batteries are NOT the same as lead acid airplane batteries and neither are the same as a Gas Recumbent Mat (RG) airplane battery.

Yes the correct battery charger is expensive. So is a destroyed aircraft battery which has been incorrectly charged. I've seen it more than once. Leroy destroyed our RG battery using old school car chargers like he would charge a car battery, the newly installed battery of the '54 170 which was up for raffle and recently won at our airport suffered the same fate when someone just through on that car charger laying in the hanger. I will not put any car charger on my RG (or airplane lead acid) battery and simply walk away thinking the auto feature will take care of it.

And if you want to know if you should remove the battery for any serious charging, specially should you over charge the battery and spew all sorts of corrosive gas in your engine compartment, come look at my corroded fire wall from just this practice.

Not to appear argumentive.... but ... I was SPECIFIC when I stated "An ordinary, self-regulating automobile charger ..."

Bruce is correct.... do NOT use a "time-design" charger, also known as a "constant-voltage" charger....which is the type to which Bruce is refering when he mentions a charger that relies "on time". These types usually have a twist-knob or windup clock built-in, but not all.

The type automotive chargers which I recommended in my first response are "constant-current" types which monitors the battery voltage and cuts itself OFF when the top-charge is complete. In fact, the two chargers I specifically recommended not only shut themselves OFF when the charge cycle is complete.... if left connected to the battery, they periodically "sample" the battery voltage and when the top-charge has dissipated ...the charger will again "top-off" the battery using short pulses. This contributes to battery longevity by preventing "sulfation" of the cells on those batteries which suffer that problem such as many lead-acids.

If frugal LeRoy did as Bruce often tells us.... if he was loathe to spend any money on modern equipment and used an old automotive constant-voltage charger... YES...it will burn up a battery to the point of going dry and warping plates and possibly causing a fire.
Do not use a constant voltage charger on aircraft batteries.

Bruce is also correct that " Lead acid car batteries are NOT the same as lead acid airplane batteries and neither are the same as a Gas Recumbent Mat (RG) airplane battery." The differences in construction are physically different and the lead acid types also use a different specific-gravity electrolyte. However, electrically and with regard to re-charging theory and practices... they operate on the exact same principles.

Any battery that is damaged or otherwise compromised should not be left in an airplane whether or NOT it is to be re-charged or used. IT SHOULD NOT BE FLOWN, EITHER!
If LeRoy's practices had been previously used on his aircraft's battery.... then it was already damaged, and using a constant-voltage charger on it yet-again ... certainly could be expected to have further damaging results.

I agree with Bruce's next comment (and is what I also previously recommended)... use an automatic charger. However it is NOT NECESSARY to buy an expensive charger, regardless of how "correct" it is as some promoter claims. Despite whether you have an ordinary lead-acid, recombinant-gas (RG), gel-cell, or AGM battery... IT HAD TO BE CERTIFIED FOR YOUR OLD CESSNA'S 1950'S CHARGING SYSTEM ... and is not so magical that it must have a Star Wars charger. What kind of charge cycle do you think that battery is under-going IN FLIGHT every time you fly.... with that old generator/vibrating-points charging system Cessna provided?

Even if your airplane has been converted to a "modern" alternator system... it is still a 1960's design... and it is no more modern in charging theory than the original system. The most recent-designs in aircraft batteries...to be certified for use in these airplanes... must be compatible with 1950's charging technology or they cannot be approved for the installation!

I stand by my earlier recommendations (reminding again that every lawyer who works for a battery/charger mfr'r tells us to remove it for charging. I guess they'd have us all pull the circuit-breakers/fuses on the generators/alternators when we fly.)

I try to remain suspect of excessive advertising claims. Prove it independently I say.

Maintaining the utmost respect for hydrogen gas. Prefer to charge aircraft battery outside the airframe.

Like many of you I studied the subject. Kept telling myself that RG does not stand for Really Good.

Ended up purchasing what I thought I would never do. Buying a battery charger that is BRANDED with a named battery! It is written on the charger unit.

Yes I purchased the Concorde BatteryMINDer 128 12 v. and love it.

Apparently the legal counsel for both the Charger and the Battery Mfg thought , we can do this.

Wouldn't an AGM charger work with a Concord RG battery? I have one of these already.

https://www.amazon.com/gp/product/B004L ... UTF8&psc=1




The reason I started all this is because my battery voltage is not holding up when I fly. I see a maximum of 13 volts when the generator is charging and usually its down around 12.4 volts which triggers my low voltage alarm on the EI. I measured the voltage of my battery at rest and it is 12.3 volts which according to the Concord manual means it is about 70-75% charged. I am wondering if my battery is going bad vs my charging system. My generator is brand new. The voltage regulator is original.

Not to disagree or agree with any of the above opinions but here is another take.
http://www.aviationconsumer.com/issues/ ... 974-1.html

13.0 is definitely too low. The Concorde RG manual says RG batteries should be charged between 13.5 and 14.5 volts over a temperature range of 115F to 0F. Low temp --> high voltage.

nippaero wrote:...The reason I started all this is because my battery voltage is not holding up when I fly. I see a maximum of 13 volts when the generator is charging and usually its down around 12.4 volts which triggers my low voltage alarm on the EI. I measured the voltage of my battery at rest and it is 12.3 volts which according to the Concord manual means it is about 70-75% charged. I am wondering if my battery is going bad vs my charging system. My generator is brand new. The voltage regulator is original.

Your voltage regulator is likely the culprit. After an engine-start... your generator should be capable of putting out 13.5 volts as a minimum.... and your ammeter should indicate very closely the same rate as the maximum rating of your generator... immediately after start and reaching 1500 RPM or so. In other words, starting your engine discharges your battery sufficiently that it requires replenishment. After your oil pressure is "up" you can safely increase RPM to 1200 or more to activate your generator "coming-in" speed. If your regulator and generator are properly matched.... the ammeter should show a very strong "positive" charge occurring... which is your charging system replenishing the battery.

Ordinarily, before take-off, your charge rate should be below 10 amps. (Otherwise your battery is not yet re-charged sufficiently to support all the appliances should you suffer a generator-failure after take-off. If you are IFR you'll need a healthy battery to get vectored out and complete the returning approach...or to get to your take-off alternate. VFR pilots may not be thinking about such matters...but it's still a good check to make before take-off as a method of regularly checking for charging-system and battery health.)

During your cruise portion of the flight your charging system should indicate 12.7-13 volts continuously.... unless you are drawing more than your charging system is producing. (An example of this might be at night, all lights ON including incandescent landing/taxi lights, etc in the terminal area. However, after getting up to the enroute phase of flight, you'll turn off those land/taxi lights and after a short period your battery should be re-charged sufficiently to indicate 12.7-13 volts being generated.)

If those conditions are not met... then your generator/regulator (or alternator/regulator) system isn't doing it's job and needs service.

The Cessna 170 Electrical Systems Service Manual has a short section on how the old/original vibrating points regulators can be adjusted. Although this is actually a job for aircraft technicians certified for the job... it's really a simple matter of adjusting the contact-points spring-tensions inside the regulator cover.

The Aviation Consumer article is a good one, but as with most aviation periodicals...they need to sell products to generate advertising income dollars. (There is a few questionable statements made, IMO.... for example when they state "Lexington, Kentucky-based Advanced Flight has a PMA-approved quick-connect plug that’s compatible with the VDC Electronics BatteryMinder line...." I don't know how Parts Manufacturing Approval was accomplished for a device which was never approved for aircraft use.
Also, they state "If you don’t want to chase fluctuations in charging system output, our advice is to stick with a flooded battery type and deal with associated maintenance that tags along..." That, to me, is a clear attempt by them not to lose the Gill battery advertisements. The charging system "outputs" have little to do with the type aircraft battery chosen, and a lot more to do with the charging system! Doh.

The point I wish to make is that this is not as much mystery as advertisers would have you believe. Again,... if these batteries are approved for installation in a 1950's airplane with automotive charging systems.... Then they MUST operate satisfactorily with automotive charging systems.

(And my Concorde RG was installed in July, 2010. It is still in good condition 7 years later (as of the Fly In this weekend to Tyler.) The only charger used on it beside the original 35A generator/regulator airplane system has been the Sears/B&D units I posted earlier. Enroute to Deming, NM convention last month ...during cruise flight... my voltage meter read a constant 12.8 or .9...(it's an analog meter) ...while my Garmin Aera 510 showed the supply voltage to be 12.7 on the "Numbers" page. This is typical for my airplane. The vibrating points regulator I have was adjusted by me when I installed it, from it's original 13.4 downward to maintain an average of 12.7 using a digital meter.) I should mention that I personally believe many batteries are killed by either disuse/long storage without proper recharging or by overcharging using "rapid" chargers. A slow charge is always the best for maintenance purposes.

George or others. I have read through the electrical service manual on adjusting the regulator and talked with my IA. I would like to measure the output voltage of the regulator. Is this done with the cowl off and engine running or do you just make small adjustments to the spring tension while the motor is off and then run it to check.